Elastic constants and thermal expansion of niobium as a function of temperature

Author

Carroll, Keith James

Date

1962

Advisor

Houston, William V.

Degree

Master of Arts

Abstract

The three Independent elastic constants of the bcc niobium structure have been determined as a function of temperature over the range 4.2°-300°K, using an ultrasonic pulse technique - the propagation of 10 Me waves in preferred directions in the crystal specimen. Values obtained at 4.2°K are, in units of 10 dyne/cm2, c11 = 25.27 +/- 0.6%, c44 = 3.10 +/- 0.6%, c12 = 13.32 +/- 3.3%. A few measurements were also carried out on the thermal expansion of niobium, from 140°-280°K, and this quantity determined at a function of the temperature. The average expansion coefficient over the whole range studied was 6.24x10 to the -6th deg -1, which agreed moderately well with earlier work by other investigators.